Based　on　the　Chaboche　unified　visco-plastic　constitutive　model,　a　visco-plastic　constitutive　model　which　can　take　into　account　non-proportional　hardening　was　proposed　for　nickel-base　alloy　at　elevated　temperature　under　multiaxial　loading.　In　the　proposed　multiaxial　visco-plastic　constitutive　model,　the　non-proportional　hardening　is　considered　as　a　change　of　kinematic　hardening　property.　The　kinematic　hardening　parameters　which　can　evolve　exponentially　with　the　cumulative　plastic　strain　and　rotation　factor　resulted　from　loading　path　were　proposed　to　take　into　account　the　non-proportional　hardening　at　high　temperature　under　non-proportional　loading.　Experimental　verification　showed　that　the　proposed　model　can　accurately　predict　the　peak　stresses　and　the　hysteresis　loop　compared　with　the　original　model　during　the　tension-torsion　loading　process　for　nickel-base　alloy　at　elevated　temperature　under　non-proportional　loading.